Quote Originally Posted by absoludely
exactly, i understand/comprehend that perfectly. i guess what i am really curious about, and something that originally put doubt into my head (as well as countless others who have thought about this), is that when the thrust from the engines starts to push the plane forward, what exactly are the wheels doing? as in, what is the speed of the wheels? (even though i realize this is arbitrary!)
The wheels are spinning and nothing else! That is the fun of it. The wheels ONLY spin, freely! Actually, the wheels will spin at twice the rate of forward motion of the plane as the treadmill is doing the same speed in reverse.

So, the plane is moving at 100knots forward and the treadmill is doing 100knots in reverse...the wheels are spinning (and ONLY SPINNING) at 200knots. They still have no affect on the plane's forward motion. All the treadmill does is spin the wheels.